This invention relates to an image exposure apparatus having an exposure unit for exposing a light-sensitive material, such as photographic printing paper, line by line as the material is transferred in a specified direction.
Conventionally, an image exposure apparatus of this kind comprises an exposure unit 101 including a lead lanthanum zirconate titanate (PLZT) device, for instance, a positioning member 102 disposed face to face with the exposure unit 101, a first pair of transfer rollers 103 located upstream of the exposure unit 101 and a second pair of transfer rollers 104 located downstream of the exposure unit 101 as shown in FIG. 11, for example, wherein image exposure operation is performed by exposing a light-sensitive material P like photographic printing paper which is gripped between the first transfer rollers 103 and between the second transfer rollers 104 and transferred over the top surface of the positioning member 102 with a digital image projected line by line by the exposure unit 101. The PLZT device is a shutter array formed of a transparent ferroelectric ceramic material, which is obtained by adding lanthanum to lead zirconate titanate, and utilizes an electro-optical effect of the material.
In the image exposure apparatus thus constructed, the light-sensitive material P would scarcely lift upward apart from the positioning member 102 by between the first transfer rollers 103 on the upstream side and the second transfer rollers 104 on the downstream side, where the light-sensitive material P is gripped, even when the light-sensitive material is somewhat curled, because it is pulled by the transfer roller pairs 103, 104 on both sides. It is therefore possible to properly expose the light-sensitive material P.
If, however, the light-sensitive material P is curled even slightly, its forward portion would lift apart from the positioning member 102, creating an out-of-focus condition and making it impossible to properly expose this portion, because the forward portion of the light-sensitive material P is not gripped by the second transfer roller pair 104 on the downstream side. Similarly, if the light-sensitive material P is curled even slightly, its rear portion would lift apart from the positioning member 102, creating an out-of-focus condition and making it impossible to properly expose this portion, because the rear portion of the light-sensitive material P is not gripped by the first transfer roller pair 103 on the upstream side. In particular, the exposure unit which exposes line by line generally has a large depth of focus and, in most cases, maximum permissible displacement of the light-sensitive material along the optical axis of the exposure unit is only about xc2x10.1 mm so that the exposure operation is likely to be affected by the curl.
Thus, it has often been necessary in the image exposure apparatus of the prior art to cut and discard the forward and rear portions of the light-sensitive material P, developing a problem that losses of the light-sensitive material are caused. A further problem has been that if the forward and rear portions were to be cut, processing capability would be decreased by as much as the time required for cutting operation.
This invention has been made in consideration of the aforementioned situations. It is therefore an object of the invention to provide image exposure apparatus which can properly expose forward and rear portions of a light-sensitive material even when it is curled.
To achieve the aforementioned object, an image exposure apparatus according to the invention comprises an exposure device for making line-by-line exposures of a light-sensitive material on an optical axis, a positioning member provided at a position facing said exposure device and having a projecting part situated on said optical axis on a side facing said exposure device, a first transfer path provided on an upstream side of said positioning member to transfer said light-sensitive material toward said positioning member, and a second transfer path provided on a downstream side of said positioning member to transfer said light-sensitive material which has been transferred passing over said positioning member further downstream, wherein the projecting part of said positioning member is located on a side closer to said exposure device than the point of intersection of an extension of said first transfer path and said optical axis and the point of intersection of an extension of said second transfer path and said optical axis, and said positioning member has on its upstream side an inclined portion for guiding a forward end of said light-sensitive material transferred from said first transfer path onto said projecting part.
According to this construction, the projecting part of the positioning member is located on the side closer to the exposure device than the point of intersection of the extension of the first transfer path and the optical axis and, therefore, a forward portion of the light-sensitive material having been transferred by the first transfer path is brought into contact with the inclined portion on the upstream side of the positioning member, guided onto the projecting part and exposed by the exposure device.
Further, a rear portion of the light-sensitive material is situated on the side closer to the exposure device than the point of intersection of the extension of the second transfer path and the optical axis when the light-sensitive material having been transferred by the first transfer path is passed to the second transfer path and transferred further downstream. Thus, the rear portion of the light-sensitive material is prevented from lifting toward the exposure device and held in contact with the projecting part so that the rear portion is exposed by the exposure device as it passes over the projecting part.
Consequently, proper exposures are made at both the forward and rear portions of the light-sensitive material even when it is curled.
Also, an image exposure apparatus according to the invention comprises an exposure device for making line-by-line exposures of a light-sensitive material on an optical axis, a positioning member provided at a position facing said exposure device, a first transfer path provided on an upstream side of said positioning member to transfer said light-sensitive material toward said positioning member, a second transfer path provided on a downstream side of said positioning member to transfer said light-sensitive material having passed over said positioning member further downstream, and uplift-restraining means for preventing said light-sensitive material from lifting from said positioning member toward said exposure device.
According to this construction, the light-sensitive material transferred by the first transfer path and the second transfer path is kept from lifting from the positioning member toward the exposure device by the uplift-restraining means. As a consequence, the whole of the light-sensitive material including its forward and rear portions is brought into contact with the positioning member, and proper exposures are made over the entire light-sensitive material.